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2017-11-20

Background  Notes

 
     
 

THE BOULTON-PAUL TYPE A QUAD TURRET TYPE A

 
     
  An article reproduced from : (source not noted....)  
     
  See also: Cheat Quad Turret for AAC

Related page : AD196A6_Murena

 

Boulton Paul was one of the two main innovators of gun turret designs for British aircraft, along with Nash & Thomson; they supplied large numbers of installations for British aircraft. Boulton Paul's designs were largely based on originals licensed from the French company SAMM (Societe d'Application des Machines Motrices), while Nash & Thomson concentrated on the FN designs originated by the firm's co-founder, Archibald Frazer-Nash. Boulton Paul's turrets were electro-hydraulic in operation; electric motors located in the turret drove hydraulic pumps that powered hydraulic motors and rams. This was more effective than electric motors alone, and did not require power developed by the aircraft's engines as did the hydraulic system utilized by the Nash & Thomson design. The turret type A was the biggest feature of the two-seat fighter Boulton-Paul Defiant. This fighter was virtually built around this turret.

The turret Type A could be traversed the full 360 degrees with the four machine guns raised from zero to 84 degrees.  The Type A turret was equipped with Browning .303 Mk II rather than Vickers .303.  The Browning guns may be compared to contemporary equivalent as follows :

    Gun Weight - - Length (mm) Speed Nbr RoF Range Range Ammo Weight Year ID
W_ID kg lb Ammo cal. Gun Barrel m/s Barrel rpm m AAC Total Bullet - AAC
MG29 11.0.kg 24.25.lb 7.50x55   - - 780

1

1100 - 1000 34.g 11.g - MG29
M60C 10.5.kg 23.15.lb 7.62x51 .30   1105 560 850

1

600 1100 1000 37.g 11.g 1957 M60C
AN/M1 9.0.kg 19.84.lb

7.62x51

.30   1455 - 850

1

1200 1400 1000 37.g 11.g 1919 ANM1
ShKAS 11.0.kg 24.25.lb

7.62x54

.30   810 585 800

1

1800 - 1000 33.g 11.g 1936 SHKS
Browning.303 10.0.kg 22.04.lb 7.70×56 .303 1346 610 818 1 1150 914 1000 33.g 11.g 1936 B303
Vickers.303 13.4.kg 29.54.lb 7.70×56 .303 930 529 762 1 1200 - 1000 33.g 11.g 1935 V303
MG170/7.92 12.0.kg 26.46.lb 7.92x57   1213 600 850

1

1000 - 1000 36.g 11.g - M171
MG810/7.92 6.5.kg 14.33.lb 7.92x57   915 - 785

1

1600 - 1000 36.g 11.g - M181
MG81Z/7.92 12.9.kg 28.44.lb 7.92x57   915 - 785

2

3200 - 1000 36.g 11.g - Z181
Ksp.m/22 18.0.kg 39.68.lb 7.90x58   1455 - 760

1

1080 - 1000 29.g 14.g - KS22
Ksp.m/32 18.0.kg 39.68.lb 8.00x63   1455 - 760

1

1080 - 1000 29.g 14.g - KS32

Boulton-Paul type A turret in a Defiant two-seat fighter Boulton-Paul Defiant . Notice the A turret just behind the cockpit

Each pair of guns was fed from an ammunition box in the lower part of the turret. 600 rounds per gun were carried, taking the weight of the turret with its armament to over 275 Kg.  Forward of the ammunition boxes were a pair of canvas bags which collected the used rounds as the guns were fired.  The gunner had a joystick type of control from which he could direct the turret traverse and gun elevation.  In case of failure, the turret could be positioned manually via rotating crank controls.  A button on top of the stick fired the guns when operated.

When installed in the turret either via a step into the turret' s rear doors, or through the hatch in the bottom of the fuselage, the gunner would plug himself in, so to speak, to enable his own supply of oxygen and radio communication with the pilot.  As the guns were in motion, pneumatically operated fairings fore and aft of the turret helped with the air flow to reduce drag.  The fairings themselves were of wooden construction.

The Type A turret was developed into many versions, adapted to the requirements for use in aircrafts such as the Boulton-Paul Defiant Mk II, Handle Page Halifax Mk.VIII, Martin Baltimore Mk I, Blackburn Roc Mk.II, Armstrong Whitworth Albemarle, Consolidated Liberator Mk II and also as training aids mounted statically in rigs or on top of vehicles.

Type A turret in Defiant fighter RAF gunners in training with type A turret

The A turret was also seen as an ideal anti-aircraft weapon for use on small warships. The A Mk II P.B.1 and 2 were fitted to some minesweepers and patrol boats. They were basically the normal Defiant turrets, but with 10 deg of depression, which meant the elevation was reduced by 10 deg to 74 deg, and only partial rotation was available. A Beaverette prototype light armoured car was also built, fitted with the A turret, apparently as an aerodrome anti-aircraft weapon for the RAF.

The Type A turret proved an efficient design, its low profile causing a minimum of drag to the aircraft. The Hele-Shaw-Beacham hydraulic variable gear system provided a very smooth operating movement in both traverse and elevation. The gunner's view was not ideal, being impeded by the guns and feed mechanism, but he had a reasonable view to his front and directly to each beam. The four Browning guns were mounted in pairs on either side of the turret, while to the gunner's front was the control table with the following operating equipment.

This control had two positions. When pulled to the rear 'Free' position the rotation drive was disconnected mechanically and the connections to the hydraulic elevation rams short-circuited through a bypass valve. When pushed forward to the 'Engaged' position, the turret was operational.

The gun master switch was a three-position switch marked PILOT, OFF, GUNNER. The PILOT position was never used and was disconnected, being in effect another OFF position; when the GUNNER position was selected the gun firing circuit was alive.

The control column - 'joystick' - was on the right of the control table projecting through a diamond-shaped aperture. Movement of the column controlled the output from the hydraulic generator, and thus the speed and direction of elevation and rotation. A grip lever on the column energised the elecrtic-motor armature when grasped, and a gun-firing button on the top of the column was operated by the gunner's thumb.

On the right of the control panel over the gun switch was the motor main switch, which when closed energised the field of the motor and was indicated by a red warning lamp. The turret could then be operated from the control column.

In the centre of the table was a red button. When this was pressed it connected a resistance in series with the motor field winding, which doubled the speed of the motor and enabled the gunner to change quickly from one target to another. The button was used only for short periods as it imposed an overload on the motor and hydraulic system.

If the power system failed the turret could be operated by a hand rotation mechanism. A small handle was stowed under the right armrest. This was fitted to a gear shaft and, with the disengaging lever to FREE, the turret could be rotated. It was also just possible to elevate the guns by pressing the back end of the breeches. To see how this turret was operated, take a look in this interesting movie. The life of an air gunner was pretty tricky !

The four Browning Mk.II guns were mounted on their sides with the cocking levers upper-most: they were cocked by the usual looped lanyard. Four 600-round ammunition boxes were fixed in front of the gunner's legs, the ammunition belts being lifted from the boxes by the gun feed mechanism over 90 degree chutes. Spent cartridges and links were collected in collapsible bags below the guns. The guns were fired by electrical solenoid sear-release units; the gun button operated a relay which energised the releases. Sighting was by a Mk.IIIA reflector sight mounted on an arm which moved in unison with the guns, the sight switch being on the left of the control table. An adjustable floodlight controlled from a switch under the sight switch enabled the gunner to clear stoppages on night operations.

Bouton Paul Turret Type A
Role four gun light turret
Manufacturer Boulton Paul Aircraft
Armament 4×Browning .303 MkII
Ammos 600 rpg in boxes within turret
Aircrafts Albermarle Halifax VIII
Baltimore I Liberator II
Defiant II Roc II
Field of fire traverse:360° elevation:0°/84°
Rotation std: 24°/sec high: 54°/sec
Gun Sight MkIIIA reflector gun sight
Ring Ř 857mm
Armor 9mm face visor
Weights empty turret 170 kg 375 lb
with ammunitions 282 kg 622 lb
Beaverette Mk III AA 4×2
Type Light AA armoured car
Manufacturer Standard Motor Co
Armament BP turret type A
Ammos 600 rpg
Crew 2 (driver + gunner)
Suspension 4x2 wheel, leaf spring
Power Standard 4-cyl 46 hp petrol
Length 3.10 metres
Width 1.73 metres
Height 2.30 metres
Range 280 km
Speed 35 km/h
Armor up to 9 mm
Weight 2.90 tonnes

CHEAT QUAD TURRET "TYPE-A" FOR ATLANTIC AIR COMBAT™

Gun turrets are essentially associated with heavy (bomber) aircrafts.  There were however a few medium sized aircrafts also equipped with gun turrets (eg: the Grumman TBF Avenger) or aircrafts equipped with a rear firing position whithout this firing position really constituting a turret in the general acceptance of the word.  With the Boulton-Paul Type-A design dating from the late '30 early '40s, it is imagined that it has been copied by others and its original armament of four Browning .303 Mk II guns replaced with other guns.  A good example is the AD196A6 Murena, for which the cheat is initially envisaged.

BP Type-A

_

AAC™ A792

_

AAC™ A130

_

AAC™ A132

_

AAC™ A127

 Empty

285.lb

 Empty

285.lb

 Empty

285.lb

 Empty

285.lb

 Empty

285.lb

 4×Brwg (.303)

88.lb

 4×MG81 (7.92mm)

58.lb

 2×MG131 (13mm)

75.lb

 2×AK44 (13.2mm)

110.lb

 2×BRZU (12.7mm)

46.lb

 4×600 rounds

249.lb

 4×500 rounds

210.lb

 2×250 rounds

120.lb

 2×250 rounds

170.lb

 2×250 rounds

175.lb

 Full weight

622.lb

 >>

553.lb

 >>

480.lb

 >>

565.lb

 >>

506.lb

 Combined RoF

4600rpm

 Combined RoF

6400rpm

 Combined RoF

1800rpm

 Combined RoF

1800rpm

 Combined RoF

1500rpm

AAC™ Turret Type A792

Whether associated with .30, .303, or 7.92mm machine guns, the general appearance would be remain the same.  However, when pretending to mount a pair of twin MG81Z (Z181 in AAC™), the barrels should be closer to each other.

AAC™ Turret Type A127/A130/A132

When associated with heavier machine guns (.50 cal or above), the number of guns would be reduced to two.  But the general apperance would remain the same.

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